Making docs/conf.py hack so readthedocs.org can "import".
Making docs/conf.py hack so readthedocs.org can "import".

These imports will not be real, but at least will allow
readthedocs.org to import and document all of our classes.

joerideturck/gcloud-python-bigtable,joerideturck/gcloud-python-bigtable,dhermes/gcloud-python-bigtable,dhermes/gcloud-python-bigtable